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Bug 562075

Summary:	kernel: vfs: add MNT_NOFOLLOW flag to umount(2) [mrg-1]
Product:	Red Hat Enterprise MRG	Reporter:	Eugene Teo (Security Response) <eteo>
Component:	realtime-kernel	Assignee:	Luis Claudio R. Goncalves <lgoncalv>
Status:	CLOSED ERRATA	QA Contact:	David Sommerseth <davids>
Severity:	high	Docs Contact:
Priority:	high
Version:	Development	CC:	bhu, lgoncalv, ovasik, williams
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	Added the MNT_NOFOLLOW option to the umount(2) system call. This prevents umount(2) from following symlinks and avoids symlink attacks on unprivileged umounts on filesystems such as fuse, samba and ncpfs.	Story Points:	---
Clone Of:	562072	Environment:
Last Closed:	2010-08-17 15:53:36 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	562072, 562078, 673177
Bug Blocks:

Description Eugene Teo (Security Response) 2010-02-05 07:39:44 UTC

+++ This bug was initially created as a clone of Bug #562072 +++

Description of problem:
[RFC PATCH] vfs: add MNT_NOFOLLOW flag to umount(2)

From: Miklos Szeredi <mszeredi>

Add a new MNT_NOFOLLOW flag to umount(2).  This is needed to prevent
symlink attacks in unprivileged unmounts (fuse, samba, ncpfs).

Additionally, return -EINVAL if an unknown flag is encountered.  This
makes it possible for the caller to determine if a flag is supported
or not (at least on kernels with this patch).

Discussion is at:
http://patchwork.kernel.org/patch/77169/

Comment 4 Eugene Teo (Security Response) 2010-06-21 23:51:49 UTC

Upstream commit:
http://git.kernel.org/linus/db1f05bb85d7966b9176e293f3ceead1cb8b5d79

Comment 5 Luis Claudio R. Goncalves 2010-06-23 16:04:09 UTC

Patch bz562075-vfs-add-MNT_NOFOLLOW-flag-to-umount.patch, backport of upstream commit db1f05bb85d7966b9176e293f3ceead1cb8b5d79, has been added to kernel -159 patch queue.

Comment 7 Clark Williams 2010-07-15 15:13:59 UTC

Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.

New Contents:
Added the MNT_NOFOLLOW option to the umount(2) system call. This prevents umount(2) from following symlinks and avoids symlink attacks on unprivileged umounts on filesystems such as fuse, samba and ncpfs.

Comment 9 errata-xmlrpc 2010-08-17 15:53:36 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0631.html